Float removal device for rotatable type heavy-media separators



Jan. 6, 1953 s. A. FALCONER 2,624,461

FLOAT REMOVAL DEVICE FOR ROTATABLE TYPE HEAVY-MEDIA SEPARATORS FiledAug. 13, 1949 s Sheets-Sheet 1 INVENTOR 570m??- 4. F41 CO/VA'A? ATTORNEY5. A. FALCONER FLOAT REMOVAL DEVICE FOR ROTATABLE TYPE HEAVYMEDIASEPARATORS Jan. 6, 1953 3 Sheets-Sheet 2 Filed Aug. 13, 1949 INVENTOR572/46 7 4. F41 co/vzw,

' A TORNEY Jan. 6, 1953 s. A. FALCONER 7 2,624,461

FLOAT REMOVAL DEVICE FOR ROTATABLE TYPE HEAVY-MEDIA SEPARATORS FiledAug. 13, 1949 V v s Sheets-Sheet 3 wbll w INVENTOR 5704/? 7/4. CO/VIA;

ATTORNEY Patented Jan. 6, 1953 FLOAT REMOVAL DEVICE FOR ROTATABLE TYPEHEAVY-MEDIA SEPARATORS Stuart A. Falconer, Darien, Conn., assignor toAmerican Cyanamid Company, New York, N. Y., a corporation of MaineApplication August 13, 1949, Serial no.11o,oee

Claims. 1 i v This invention is concerned with an improvement inheavy-media separation of solid particles. In particular, this inventionis concerned with an improved apparatus and method for handling particlemixtures of materials of different specific gravity, the material oflesser specific gravity having present a preponderance of large pieces.

In recent years, a growing industrial interest has developed in variousoperations for the separation of solid particles by their differences inspecific gravity. In such processes, a mixture of particles havingdiflerent specific gravities is immersed in a fluid having a densityapproximating, and usually between, the gravities of the particles to beseparated. In the more usual case, where the fluid density isintermediate the specific gravities of the solids to be separated, theparticles are separated into a float" fraction of lesser gravity thanthe fluid and a sink fraction of greater specific gravity than thefluid. The present invention is primarily concerned with such types ofoperations.

One of the primary requisites of the'heavymedia separation is that thesize range of the particles to be separated be capable of being handledby the apparatus. Since the particle size which must be treated may varyfor numerous reasons, this limitation may be serious in some cases.Either or both gravity fractions may be present over a wide size rangeand either may be preponderant in quantity. Where the float fraction iscomprised of particles varying in size over a wide range, nosatisfactory handling method or apparatus has been available. This istrue whether the float alone or both fractions contain both fine andlarge pieces.

The present invention is particularly concerned with the handling ofthese types of float fractions. Handling of some types of coal are goodexamples. Slate, which may be present as the lesser fraction, usuallyconstitutes the sink. The float fraction often will contain not onlysmall fines but intermediate sizes up to very large pieces. Some of thelatter often exceed 6 inches or more in average diameter, and some maybe as large as several feet. There is thus presented a physical problemof actually removing all the differently-sized float fraction materialfrom the apparatus.

In the past, a number of more or less conventional types of heavy-mediaseparatory vessels have been developed. In substantially all of these,the lesser gravity fraction is removed simply by over-flowing the floatfraction, together with some of the separatory fluid, over a restrictedlip or weir. As long as the float fraction comprises relatively smallparticles, this method of removal presents no serious problem.

However, when this fraction begins to contain large pieces, a number ofdifliculties arise. In addition to the previously-noted problem ofphysicallyremoving the large pieces from the vessel, another problem,really an outgrowth thereof, is presented. If suflicient overflow offluid to carry out the large pieces is utilized, it becomessubstantially impossible to maintain practical hydraulic balance withinthe separatory vessel. Further crushing or grinding to reduce theoversize pieces is not practical as a solution since the resultantproduct will ordinarily contain an excessive amount-of fine.

It is, therefore, the primary object of the present invention to devisea process and apparatus whereby a particles mixture in which the floatfraction may contain appreciable amounts of both large pieces andrelatively small fines, may be handled efllciently. It is a furtherobject of the invention to provide a process and apparatus which notonly permit the handling of feed but also permit maintenance ofrelatively stable hydraulic conditions in the principal zone ofseparation within the vessel. A still further object is to provide anapparatus which is'easily maintained and is operable over extendedperiods with minimum attention.

In general, the objects of the present invention have been met by theconstruction of a relatively simple separatory vessel. The lattercomprises a rotary chamber, provision for removing the fine float as onefraction being specially provided together with special handlingequipment for removing all the sink as a second fraction and the coarsefloat as a third fraction. Motivation of the apparatus involves onlyrotation of the vessel. This is a particular advantage in that no movingparts are necessarily operated within the separatory fluid in which thematerial being treated is immersed. In this way, there is no problem ofabrasion from the particles which may be quite hard.

The invention willbe more fully discussed in conjunction with theaccompanying diagrammatic drawings, in which:

Figure 1 is a front elevation showing the arrangement of the elements ofthe present invention within the vessel;

Figure 2 is a vertical elevation partly in section along line 2-2 ofFigure 1;

Figur 3 is an enlarged partial section of a portion of Figure 2;

Figure 4 is a vertical section of a modification of Figure 3;

Figure is a front elevation of the modification shown in Figure 4;

Figure 6 is a horizontal view, partly in section, .of the modificationshown in Figure 3 and, with Figure 7, which is aiso a horizontal view,partly in section, of a still diflerent modification of several methodswhereby extra large feed is handled; and

Figure 81s a partial horizontal elevation, partly in section, showing astill further modification.

As will be seen from the drawings, the separatory vessel propercomprises a closed vessel, generically indicated as I, mounted to rotateabout a horizontal axis. This vessel, in general, may be given anycylindrical surface. Preferably, however, as best shown in Figure 2, theouter shell is not a simple cylinder, but is so designed that onesection is of definitely larger diameter than the remainder. As shown inFigure 2, this comprises a relatively narrow central cylindrical section2 on either side of which is a conical section 3 and 4. These, as shown,are essentially conical frustrums. Their larger diameters coincide withthe diameter of the cylindrical central section, and the smallerdiameters are fitted with annular endplates 5 and 6 respectively.

It will be noted that annular endplate 6 is of larger outer diameterthan is endplat 5. The end formed by plate 5 will be designated, for thepurpose of this description, as the feed end. The opposite end will bedesignated as the discharge end. Probably, as best seen in Figure 2, theouter edge of the opening in annular disc 8 is surrounded by a conicalfiange I.

Also, as seen from Figures 1 and 2, by this arrangement, when thecylinder is mounted in horizontal operating position and partiallyfilled with the separatory fluid 8, the depth of the latter will reachan overflow level. At this level it will be retained by endplate 5 butwill overflow the bottom of the opening in the annular endplate 6.Conical fiange I leads this overfiow to a suitable launder 9. By meansof this launder 9, it is conducted to any suitable subsequent operation,which, forming no part of the present invention, is not illustrated.

It will be seen that cylindrical section 2 forms a low point in theseparatory fiuid. ,This has the advantage that the sink fraction is morereadily collected in a restricted area, i. e., at the low point,

and is thereby capable of being more efliciently removed from theapparatus, as will be described below.

Within the separatory vessel I, surrounding the opening of annular disc6, is a series of lifter plates I0. Also within the cylindrical sectionof the vessel is a second set of lifter plates II. These plates II aresubstantially the same width as the length of cylindrical section 2 andshould be equi-distantly spaced completely about this section.

As shown in Figures 1 to 3 and 6, the inner ends of the set of fioatlifters is a single annular plate I2, the opening in plate I2 beingsomewhat larger than the opening in plate 6. The fines fioat whichaccumulates near the surface of separatory fiuid is thus enabled to fiowover the opening in plate I2 and out the opening in plate 6. Because asingle plate I2 comprises the ends of all of the blades I0, sinkmaterial which has not quickly classified and dropped is thus preventedfrom methods.

' entering the area from which it can be picked up by the lifter bladesI0.

This is probably best shown in Figures 3 and 6, in which it will be seenthat the fine float at or near the, surface of the fiuid is passing outby .overfiow over the edge of plate 6 down over flange 1 and intolaunder 9. If the larger float material, as shown by the lighter coloredparticles, accumulates near the surface, but does not ride as high intothe top layers, it is able to pass over the edge of the opening in plateI2 but falls suiTiciently so that it cannot be overflowed over the lipof the opening in plate 6. It is, accordingly, picked up and carriedforward by the lifter blades I0. As probably best seen in Figure 3, thebottoms of the lifter blades Ill are composed of mesh or screen I3 sothat as the blades lift solids it will be possible for at least a partof the liquid carried on the particles to drain directly back within theseparatory vessel. Further, at the same time the sink particles whichare near the surface of the fluid, shown in Figure 3 as dark particles,are prevented by plate I2 from entering the area in which they can belifted by the blades or lifters ID.

A downwardly-sloping feed trough I4 extends into the apparatus throughthe opening in the annular rear wall 5. Trough I4 in turn receives thematerial from a suitable chute I5 from a conventional feed launder, bin,or the like. Trough I4 is also provided with a suitable conduit it whichenters the chute just outside the separatory chamber. separatory mediumis introduced into the feed chute through conduit I6 to assist the fiowof feed and to pre-wet the particles before they are introduced into theseparatory vessel. It has been noted that the opening in the annularendplate 5 is considerably smaller than the opening in the annularendplate E. The difference in diameter should be such as to prevent anyoverflow of separatory fluid through the opening in endplate 5.

Mounting of the separatory vessel may be in accordance with any ofseveral conventional One such is shown in the drawings. It will be seenthat around the outer periphery of the cylindrical section 2, thecylinder is provided with gear teeth Il, which mesh with and aresupported by a suitable pinion I8. The latter is mounted on a suitableshaft I9, and the latter is driven by a suitable gear 20. Gear 20 is inturn powered from some conventional source, which. forming no part ofthe present invention, is not shown.

As a further support, and to strengthen the separatory vessel, theconical section 4 is surrounded by an annular ring 2|. Ring 2| restsupon and is supported by a series of idler rolls 22, which in turn aresupported in any conventional manner. As seen in Figure 1, ring gear IIalso rests upon and is supported by a plurality of idler gears 23. Sincethese do no driving, they may be supported in any conventional manner,which forms no part of the present invention.

Extending into the separatory vessel in an upwardly-slanting direction,is a fan-shaped launder 24. This launder is wide enough at the broaderpart of the fan to receive any material dropped by lifter plates III asthey become inverted through rotation of the vessel itself. Launder 24carries the material, which comprises the coarse fioat fraction, to asuitable conduit 2!, by which the material is conducted to any othersubsequent operation.

Immediately above fan-shaped launder 24 is a ammo:

second and wider fan-shaped launder 28. 'Launder 26 extends into thevessel sufllciently far, and is sufllciently broad, to receive all thematerial dropped from the lifter plates H as the latter are inverted atthe top of their rotary travel. The narrow end of launder 26 conductsthis material, which is the sink product, to a suitable conduit 21, bywhich it too is conducted to some subsequent operation, which is not apart of the present invention. Launder 9, which was previously noted,also connects to a similar conduit 28,

whereby the flne float fraction is conducted to any suitable destination-as may be desired.

It should be noted that fan-shaped launder 26 should be so located andbe of sufflcient size so that material dropped from lifter blades IIcannot be picked up in, or caught by, launder 24. As best seen in Figure2, launders 9, 24, and 26 are provided with conduits 29, 30, and 3 i,respectively, by means of which medium may be introduced into thelaunders. This is done to insure movement of the discharged fraction andto keep the launders clear.

If necessary, these various conduits may be extended into the vessel,through the opening of plate 6, to a point at or near the top oflaunders 2s and 25.

Operation of the apparatus is believed to be apparent from the foregoingdescription. Feed to be separated, pre-wet by separatory fluid fromconduit i6, is introduced into the separatory fluid within the chamber.The more dense fraction gradually settles to the bottom of theseparatory fluid and is accumulated at the low level constituted by thelarger diameter cylindrical section 2. Rotation of gear l8 causesrotation of gear I! and in turn this motivates the cylinder. Rotation ofthe latter causes movement of both sets of lifter blades raising boththe coarse float and the sink fractions up through the fluid to theupper part of the chamber. In the normal progress of rotation of thevessel, both sets of lifter blades become inverted and discharge theircontents into the respective launders 24 and 25. From the latterproducts are taken from the apparatus through conduits 25 and 21.

The less dense fraction which floats to the surface of the separatoryliquid and contains the flner particles is differently handled. Floatingat or near the upper surface of the separatory fluid, discharge of thisfraction may best be seen in Figure 3. The natural tendency of thedensity differential effect produced by the overflow is to de-water themedium. The upper surface of this overflow will have a densitypractically that of water and contain little or no solid material. Thedensity, however, builds up very rapidly in successive layers until ithas reached about separation density at the level of the overflow lipitself. Fine particles of float which ride in these layers pass out ofthe chamber over the apron I and into launder 9. From there. they passinto conduit 28 and so pass out of the system of the present invention.

It is usually desirable to maintain the fine float and coarse floatfractions separately, hence the provision of the separate chutes andlaunders. However, it may not be either necessary or desirable to do so,and in such case the discharge may be directed into acommon chute; i.e., if so desired, launders 9 and 24 may both discharge into a commonconduit such as conduit 28. However, since the products are separatelycollected, it is usually desirable to maintain them separately tosimplify subsequent handling. It is an important advantage of thepresent invention that this can be done. This advantage will seldom besacrificed.

The illustrated arrangement provides that most of the returnedseparatory fluid be used to pre-wet the feed, although some is used toaid the discharge of the various products. generally found to be apreferable arrangement. Ifso desired, however, it is perfectly feasibleto provide a separate conduit for introducing a part of the fluiddirectly into the vessel without being used to pre-wet the feed.Similarly, if so desired, additional conduits may be provided enteringthe chamber through the opening in endplate 5, and extending down intothe separatory fluid. This enables introducing separatory fluid of anydesired density at different levels within the vessel. Since theselatter arrangements actually form no part of the present invention, theyhave not been illustrated, even though their use has been contemplated.

While the foregoing descriptions have been largely concerned with theparticular apparatus elements of specific design, it is obvious that theinvention is not necessarily restricted thereto. However, functionalequivalents of the various elements are necessary. The exact design ornature of these elements is not critical. For example, differentsupporting and rotary drive systems may be used, The contour of theseparatory vessel itself may be varied, the specific shape, inclinationand number of the lifter blades or buckets may be varied. The exactlocation of the sink lifter blades may be widely varied with designchanges. Functionally, the following elements must pertain. There mustbe a rotatable conical or cylindrical shell. The shell, to constitutethe vessel, must have annular endplates. The central opening of thedischarge end must be appreciably larger than the central opening of thefeed end. There must be a means for introducing the material to betreated into the vessel. There must be means for introducing separatoryfluid into the vessel. There must be a lifting mechanism adapted toraise the sink out of the separatory fluid, and remove the raised sinkwithout admixing it with the float fraction. There must be provision fora continuous fluid overflow to remove the flne float. There must be alifting mechanism adapted to raise that portion of the float fractiontoo large to be overflowed with the minimum amount of medium required toremove the fine fraction. There must be means for removing the raisedfloat fraction without its becoming admixed with the sink. So long asthese functional elements are present, the

process of the present invention may be operated,

regardless of the remaining apparatus limitations, such as the specificshape of the launders, delivery chutes, and the like. The arrangementshown in the drawings has been found to be preferable.

As seen in Figures 1 to 3 and 6, the ends of lifter blade ID arecomprised of a single annular ring I2. This is a simple form ofconstruction. As was noted above, some such type of obstruction isnecessary to prevent the smaller and more slowly settling sink particlesfrom being carried up and out with the coarser float material. The useof a solid annular plate for this purpose has certain limitations itlimits the overflow to the material whichwill pass over the two arcuateopenings, one in plate l2 and the other in plate This is 0. It may bedesirable to provide a larger-opening in the inner plate, also it-may bedesirable to be able to change the size of this opening from time totime without completely rebuilding the vessel. An arrangement for thispurpose is shown in Figures 4 and 5.

As shown in Figure 4, the lifter blades need not have a solid end inthis form, but the screen or mesh [3 forms not only the bottom but alsothe sides of the plates. Closely adjacent to the ends of the lifterblades is mounted a U-shaped solid plate 32. This may be readilysuspended in any desired manner from the same frame work which supportsthe fan-shaped launders 24, 26, or their mechanical equivalent, Inextent, plate 32 should be of suflicient width and depth to prevent thesmaller and lighter of the sink particles from entering the zone inwhich they can be picked up by the lifter blades. In this manner, a widebut shallow opening, the bottom of which is substantially parallel tothe liquid level, can be provided for the passage of the fine float andfluid over the plate. ,The difference in the effective area of theopenings may be seen by comparing Figures 5 and 8 As shown in Figure 6,the use of an annular endplate I! to form the ends of lifter blades orbuckets It prevents passage into the zone in which they can be lifted byblades IU of float fraction particles too large to pass over the armatelip of the plate. In such a case, a compromise construction can beutilized. This is best shown in Figure 7. Each of the individual lifterblades or buckets I0 is provided with its own individual endplate 33. Inthis way particles which are too large to pass over the arcuate lip maypass through the opening between the lifter blades or buckets into thezone from which they can be carried upwardly and out of the fluid by thelifters.

In order to provide more efllcient handling, it may also be desirable insome cases to shape or position the lifter blades for the float materialsomewhat differently. For example, it may be desirable to insurecollection of the material taken up by the blades at or near the outerwall. For this purpose, the blades or buckets may be given a slantingbottom. This is shown in Figure 8. Other similar modifications may bereadily made.

I claim:

1. A heavy-media separatory apparatus comprising in combination acylindrical separatory vessel mounted for rotation about a substantiallyhorizontal axis, an annular end plate secured to said vessel at the feedend thereof, means for introducing particles to be separated into saidvessel from the feed end thereof, means for introducing separatory fluidinto said vessel, a second annular end plate secured to said vessel atthe discharge end thereof, the central opening in said second-mentionedannular plate being of appreciably larger diameter than the opening insaid first-mentioned plate, the said second-mentioned annular platebeing so constructed and arranged that a relatively shallow weir isprovided over which a fine float fraction overflows. a plurality offloat lifter blades arranged in spaced relation and extendingsubstantially horizontally outwardly from the inner peripheral edge ofsaid second-mentioned annular plate so as to remove from the zone ofsaid weir a coarse float fraction too large in size to overflow saidweir, at least the bottom portions of saidblades being composed offoraminous material, an annular baille at the in- 8 ner ends of saidblades, the central opening in said baiile being larger than the openingin said second-mentioned annular plate a plurality of sink lifter bladesarranged in spaced relation and extending substantially horizontallyoutwardly from the inner periphery of said vessel, a first dischargelaunder positioned adjacent to'the discharge end of said vessel toreceive said flne float fraction, a second discharge launder extendinginteriorly of said vessel from the discharge end thereof to receive saidcoarse float fraction deposited thereon by said first-mentioned set oflifter blades, a third discharge launder extendin interiorly of saidvessel from the discharge end thereof to receive a sink fractiondeposited thereon by said second-mentioned set of litter blades. andmeans to rotate said vessel whereby said sink and coarse float fractionsare carried forwardly by said sets of lifter blades so as to bedeposited on said launders.

2. A heavy-media separatory apparatus comprising in combination aseparatory vessel mounted for rotation about a substantially horizontalaxis, said vessel being composed of two irustoconical sections joined attheir larger diameters to an intermediate section oi. a diameter thatcoincides therewith, an annular end plate secured to said vessel at thefeed end thereof, means for introducing particles to be separated intosaid vessel from the feed end thereof, means for introducing separatoryfluid into said vessel, a second annular end plate secured to saidvessel at the discharge end thereof, the central opening in saidsecond-mentioned annular plate being of appreciably larger diameter thanthe opening in said first-mentioned plate, the said secondmentionedannular plate being so constructed and arranged that a relativelyshallow weir is provided over which a flne float fraction overflows, aplurality of float lifter blades arranged in spaced relation andextending substantially horizontally outwardly from the inner peripheraledge of said second-mentioned annular plate so as to remove from thezone of said weir a coarse float fraction too large in size to overflowsaid weir, at least the bottom portions of said blades being composed offoraminous material, an annular battle at the inner ends of said blades,the central opening in said baflle being larger than the opening in saidsecond-mentioned annular plate a plurality of sink lifter bladesarranged in spaced relation and extending substantially horizontallyoutwardly from the inner periphery of said intermediate portion of saidvessel, a first discharge launder positioned adjacent to the dischargeend of said vessel to receive said flne float fraction, a seconddischarge launder extending interiorly of said vessel from the dischargeend thereof to receive said coarse float fraction deposited thereon bysaid first-mentioned set of litter blades, a third discharge launderextending interiorly of said vessel from the discharge end thereof toreceive a sink fraction deposited thereon by said secondmentioned set oflifter blades, and means to rotate said vessel whereby said sink andcoarse float fractions are carried forwardly by said sets of litterblades so as to be deposited on said launders.

3. An apparatus according to claim 2 in which said baiiie is an annularring unitarily attached to the inner ends of said float lifter bladesand forms pockets therewith.

4. An apparatus according to claim 2 in which said battle is mountedindependently of the rotatable elements of said combination.

5. An apparatus according to claim 2 in which each of said float lifterblades comprises a fivesided, open-tap box, at least the bottom of whichis of screen material, the openings in which are sufliciently small toretain fine particles but sutflciently large to pass media solids. 5

' STUART A. FALCONER.

REFERENCES CITED Number The following. references are of record in the10 Number file of this patent: I

UNITED STATES PATENTS Name Date Chance July 12, 1927 15 Number Re.16,674

